You can use the beam system family to create various beam systems for bays of varying geometry, including arced, polygonal, and cantilevered. The following example provides a method for creating a cantilevered beam system.
Begin with a bay that is similar to the one shown in the following illustration of a partial plan view:

Partial Plan View
Structure panel
Beam System.
Beam System panel
Sketch Beam System
Draw panel

Pick supports
Mode panel
Finish Edit Mode. The cantilevered beam system displays.

Finished cantilevered beam system